This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Infection with MRSA has become a pandemic over the past 10 years, but the molecular basis for the MRSA pandemic remains unknown. The purpose of this study is to determine whether the newly acquired ACME genetic element of CA-MRSA is the factor directly responsible for enhanced human skin colonization. In this pilot study we will identify 5-20 healthy adults previously colonized with MRSA USA300 on their skin or nose. Each subject will be inoculated with their own MRSA isolate, in order to identify the optimal inoculum and safety parameters for MRSA survival on the skin.